In general, mobile communication systems have been developed to provide communication while securing mobility of users. With the rapid development of technologies, such mobile communication systems have reached a stage of providing high-speed data communication services as well as voice communication. Recently, standard operation from 3GPP to Long Term Evolution-Advanced (LTE-A) is in progress as one of next generation mobile communication systems. LTE-A was aimed at standardization completion in late 2000, and is a technology having a higher transmission speed than the currently provided data transmission rate and realizing high speed packet-based communication.
As the 3GPP standard evolves, a method for easily optimizing a wireless network as well as a method for raising a communication speed is under discussion. In a conventional mobile communication system, a cell having a small-sized service area is frequently utilized for increasing capacity and reducing shadow areas. Because of a small-sized service area, many problems occur, such as frequent failure of handover. Nevertheless, application of a system variable which is suitable for a small-sized service area or development of operation mechanism is not specifically prepared.